Not Applicable
Not Applicable
The present invention relates to dispensers for volatiles such as scents, insect control active ingredients, and the like. In particular, it relates to such dispensers that use a fuel burner.
There are a variety of known dispensers for volatiles that employ heat from a flame or from catalyzed combustion to dispense volatiles from volatile-impregnated substrates. Citronella candles mix the volatile into the fuel itself. However, this leaves the candle flame exposed.
U.S. Pat. No. 692,075 shows the use of heat from the flame of a conventional oil lamp to dispense volatile ingredients held exposed to the ambient air on a mesh mounted on a lamp chimney, above the lamp""s flame. The disclosure of this patent and of all other publications referred to herein are incorporated by reference as if fully set forth herein. The volatile material being heated by this device is positioned above the lamp chimney and thus is directly exposed to ambient air currents, which can cause uneven heating and cooling of the volatile material. The exposed location of the material being heated also allows it to be touched or disturbed by a passing child or animal. Furthermore, it is immediately visible to a user so that charred material can present an unsavory sight.
U.S. Pat. No. 143,583 discloses a fumigator in which an alcohol lamp is placed at the bottom of a metal chimney. A cup to hold an otherwise uncontained liquid fumigant is suspended within the chimney at its top, and a perforated lid closes the chimney. The lamp heats the liquid fumigant, and vapor escapes through the perforations of the lid. Handling the uncontained liquid fumigant and gaining access to and refilling the cup can be inconvenient and risk spillage.
Petzwinkler, South African patent abstract 94/5537, discloses an oil lamp equipped with a metal mosquito mat holder that is positioned beside, as opposed to over, the lamp""s flame. Heating radiating from the flame heats a metal holder from that side of the holder which is presented toward the flame. A conventional mosquito mat is then held vertically on the opposite side of the holder, away from the flame. By this means, the mat is shielded from direct exposure to the flame or its combustion products, albeit it is heated to drive off the volatiles contained in the mat.
The Petzwinkler dispenser provides a visible flame. However, this dispenser has a mosquito mat holder that holds a mat beside the flame, in open view of a user, detracting from the pleasing visual effect of the flame itself. Also, one must remove the dispenser""s chimney to gain access to a spent mat to replace it.
U.S. Pat. Nos. 5,700,430 and 3,778,924 each employ butane as a fuel for a flame or a catalytic burner, using a replaceable fuel tank. In U.S. Pat. No. 5,700,430 a mosquito mat is laid on top of a metal plate. Heat is conducted from the location of a flame to the metal plate by means of intervening, heat-conductive parts. In a subsequent version of the device that otherwise closely corresponded to the embodiment shown, a butane flame was enclosed within a metal, rectangular, open-ended box. The box was heated by the flame, and the flame""s combustion products exited an open end of the box to be vented from the device. A mosquito mat was positioned on top of the box to receive heat conducted through the metal box from the flame. The butane flame, heat-conductive parts, and mosquito mat were all held within a protective heat box.
U.S. Pat. No. 5,700,430 thus relies on indirect heating. The volatiles from the hottest places on the mat are released fastest. Consequently, the mat""s volatiles are discharged unevenly, with the possibility that volatiles at locations remote from the attachment point may never be discharged before the mat""s overall release rate becomes so low as to require replacement of the mat.
In U.S. Pat. No. 3,778,924 a mosquito mat is held exposed to the ambient air on a metal sole plate over a catalytic burner fueled by butane drawn from a replaceable, pressurized tank. However, the mat is not enclosed in a heating chamber.
Other patents disclose assemblies that rely on an electrical heater (as distinguished from a fuel burning heater) to heat the volatile carrier. See e.g. U.S. Pat. Nos. 2,513,919, 2,942,090, 4,849,181 and 5,111,477. This restricts the portability of the device (it cannot easily be used at camping or picnic sites which do not have electrical power).
U.S. Pat. No. 5,722,199 discloses a flea trap (without a volatile heater) having a removable tray that slides into a slot in the flea trap. The slot has keying structures that restrict access into the slot. To enter, a tray must present a complementary cross-sectional profile to the slot.
There are also a number of other known insect repellent/killing devices which provide a heat source under a platform designed to support a pad that has been impregnated with the insect control active ingredient. Some use a liquid fuel such as alcohol that is burned in an open flame, or directed to a catalyst mesh where it combusts.
In some cases the platform is an open grid. In others it is a flat metal plate heated from beneath. Some of these systems also provide a separate grid structure which snaps or swings over the carrier for restricting access to the heated mat during operation. These systems typically do not provide a light source through transparent sides of a heating chamber (e.g. they are designed purely for insect control).
It can therefore be seen that there is a need for an improved heated volatile dispenser.
The invention provides a heated volatile dispenser for dispensing volatile ingredients from a volatile carrier. xe2x80x9cVolatile ingredientsxe2x80x9d include (without limitation) perfumes and other air quality modifying materials, as well as insect control ingredients. xe2x80x9cInsectxe2x80x9d includes arachnids and other similar, small animals commonly controlled in conjunction with insects. xe2x80x9cInsect control ingredientsxe2x80x9d are defined as including (without limitation) insecticides, repellents, and other development or behavior modifying materials. One highly preferred insect control agent is d-cis/trans allethrin.
A xe2x80x9cvolatile carrierxe2x80x9d is a material or structure for holding a volatile ingredient for dispensing. xe2x80x9cMatsxe2x80x9d are one common type of volatile carrier often used with insect control ingredients and are defined as including (without limitation) woven, felted, or otherwise formed fibrous or cellulose materials; as well as molded, extruded, cast, or otherwise formed polymeric, ceramic, and clay materials, together with other convenient materials loaded with volatile ingredients, whether by impregnation, printing, or otherwise. Volatile carriers can also be metal or plastic cups holding a volatilizable gel, cups holding a gel, powder, or liquid retained in the cup by a volatile-permeable membrane, or any other convenient means for holding a material to be volatilized by the application of heat. However, uncontained liquids or powders, together with liquids or powders held in open cups or similar containers, are excluded from the term xe2x80x9cvolatile carrierxe2x80x9d, as used herein.
In one form, the heated volatile dispenser of the invention has an enclosed heating chamber having chamber walls, a ceiling, and exit vents in the ceiling or chamber walls or both, the exit vents communicating between the interior of the heating chamber and the outside air. A heating chamber will be understood as being xe2x80x9cenclosedxe2x80x9d if it has solid walls and a solid ceiling and either a closed or an open bottom, one or both of the ceiling and walls being equipped with holes, slots, or other vents. Particularly preferred are permanently enclosed structures.
The dispenser also has a heat source that preferably is a fuel burner. The fuel burner can be a candle, a burner using a solidified combustible liquid such as conventional gelled alcohol, a burnable solid, a pressurized gas burner, a wick that is fueled with a combustible liquid, a catalytic heater burning a gas or liquid fuel, or any other convenient means for combusting a fuel.
The heated volatile dispenser also includes a carrier holder that is positioned to receive and hold a volatile carrier at a location above the fuel burner and contained within the heating chamber. An air-flow path is provided to guide hot gases, rising from the fuel burner by convection, past the carrier holder to heat a volatile carrier held in the carrier holder. The air-flow path is preferably defined, at least in part, by internal surfaces of the heating chamber walls. Heating is accomplished by the direct exposure of the volatile carrier to gases heated by the fuel burner. Preferably, the hot gases include hot combustion products from the fuel burner. The air-flow path then directs the hot combustion products through the exit vents to escape from the dispenser. As the volatile carrier is heated by the gases, volatile material is released and is carried out of the dispenser with the escaping hot gases.
In one form the carrier holder can be a slot in the chamber wall through which a volatile carrier is inserted, with the slot being a sufficiently snug fit for the volatile carrier that the parts of the volatile carrier projecting within the heating chamber are held in position by the snug contact between the slot and the volatile carrier. Also, a possible carrier holder can be a slot in the heating chamber ceiling, for use with a volatile carrier that is designed to be inserted downwardly through the slot and to hang from the edges of the slot from side tabs, a handle, or other parts of the volatile carrier that, because of their size or geometry, remain outside of the heating chamber, resting on outer surfaces of the ceiling.
Alternatively, the carrier holder may be an essentially open, either vertically or horizontally disposed, rack that leaves the mat or other volatile carrier held in the carrier holder directly exposed to hot gases rising in a convective flow from beneath. Alternatively, the carrier holder can be a generally horizontal heat-conductive sole plate that supports the volatile carrier. While the upper surface of the volatile carrier remains directly exposed to the hot gases from the fuel burner, the under surface of the volatile carrier is in contact with and heated by the sole plate, with the under side of the sole plate being exposed to the flow of hot combustion products from the fuel burner or to heat otherwise received from the fuel burner.
Depending on the materials chosen and the carrier temperatures desired, it is also possible to include a baffle spaced from and preferably located beneath the carrier holder and interposed between the fuel burner and a volatile carrier being held in the carrier holder. The baffle functions in part to mix hot combustion products from the fuel burner with air in the heating chamber prior to their reaching the volatile carrier. The result is believed to be a reduction of the tendency for a hot spot to form at a point on the volatile carrier directly above the fuel burner. Instead, the baffle causes a more even heating of the volatile carrier, whether the volatile carrier is heated solely by direct exposure to the hot gases or by a combination of direct exposure to hot gases and heat conducted through a sole plate.
The baffle can also function to more evenly distribute heat in another way. If the baffle is so located as to be heated by hot gases contacting the baffle from below, and if the carrier holder is spaced above the baffle, then the hot baffle serves as a radiant heater, supplementing heat delivered by a volatile carrier""s direct contact with the hot gas flow by providing broadly distributed radiant heat to the volatile carrier.
Alternatively, the holder can be in the form of an oven located within the heating chamber. xe2x80x9cOvenxe2x80x9d shall mean any substantially enclosed sub-chamber located within the heating chamber walls and made, preferably, of a heat-conductive material. The oven has oven walls and is positioned within the air-flow path. By this arrangement, the oven is heated by hot gases rising from the fuel burner. The oven holds a volatile carrier within the oven to receive heat radiating inwardly from the oven walls, an arrangement that provides for a more even heating of the volatile carrier. The oven preferably has openings sufficient to admit hot gases rising from the fuel burner so that they may directly contact the volatile carrier, and in any event has vents to allow volatile materials released from the volatile carrier to escape from the oven.
Although the fuel burner can be located beneath a heating chamber that has an open bottom, preferably the fuel burner is contained within the heating chamber itself. This arrangement contributes to the control and isolation of the convective flow of hot gases rising from the fuel burner and can also provide containment and protection for a burning flame. Thus, the walls of the heating chamber above the fuel burner can define the air flow path and limit the effects of breezes and other air movement external to the volatile dispenser.
It is sometimes desirable to reduce the temperature of the combustion products prior to their acting to heat the volatile carrier. To help achieve this the heating chamber walls can be equipped with cooling vents communicating with the air outside of the heating chamber to cause unheated air to be drawn into the heating chamber by the passing flow of heated gases, to mix with and partially cool the hot combustion products from the fuel burner prior to their reaching the carrier holder. The cooling vents can be provided at any point in the air flow path, but preferably they are located at a point in the chamber walls at or above the level of the fuel burner but beneath the level at which a volatile carrier is held.
Although the fuel burner may burn fuel catalytically or otherwise without a flame and still fall within the breadth and scope of the invention, it is highly preferred that the fuel burner support a luminous flame positioned within the heating chamber and that the heating chamber walls include a light-transmitting portion, whether clear or translucent, that allows light from the flame to be visible to a user of the dispenser. This provides a ready means for a user to confirm that the fuel burner has been lit and continues to burn, and it also provides a use-up cue for the fuel. But, more importantly, the flame provides light and aesthetic appeal, in much the same way that a citronella candle is valued in great part for its light. However, it is preferred that the carrier holder be positioned within a portion of the heating chamber whose walls are opaque so that the holder is not visible through the chamber side walls.
The mats or other volatile carriers become exhausted and are designed to be replaced. To achieve this an insert slot communicates between the interior of the heating chamber and the exterior of the heated volatile dispenser, so that a fresh volatile carrier can be inserted through the insert slot to be held by the carrier holder. The insert slot can be in either the chamber walls or the ceiling of the heating chamber.
It can be important to prevent the use of a volatile carrier not intended for use with a particular volatile dispenser, to not mistakenly use, for example, a volatile carrier loaded with insecticide in a dispenser intended to supply perfume for indoor use. Therefore, it is preferred that the insert slot include keying structures that impart a cross-sectional profile to the insert slot that so restricts access thereto as to prevent the insertion of any volatile carrier not capable of presenting a non-interfering cross-sectional profile to the cross-sectional profile of the insert slot. This makes it easier to ensure that only volatile carriers will fit a dispenser that are appropriate to a particular purpose or that are designed for use with the specific temperatures generated by the volatile dispenser. Also, the keying structures can be used to require that the volatile carrier be insertable only with a pre-determined side up or down. This can be important if the volatile carrier is, by way of example only, a gel cup that must be inserted so as to open upwardly. As examples, the keying structures can define a cross-sectional profile that includes either or both of angularly intersecting and curved sections.
Volatile carriers have a section treated or loaded (e.g. paper impregnated with liquid insecticide) with the volatile material to be dispensed, and this section may itself be formed with a functionally required cross-sectional profile such as those just described. Alternatively, the volatile carrier can include a handle in addition to a volatile-treated section, and the keying structures of the insert slot can be formed to present a non-interfering cross-sectional profile with respect to at least a portion of the volatile carrier and an interfering cross-sectional profile with respect to the handle for the volatile carrier.
In one embodiment, the heated volatile dispenser includes a fuel tank, containing fuel under pressure, and a fuel transfer route by which fuel can be transferred to the fuel burner in controlled amounts. Valves, constricted flow paths, wicks, pressure step-down controllers, or any other means may be used to control the delivery of pressurized fuel to the fuel burner in an amount sufficient to maintain combustion at a convenient level, and a variable valve may be used to allow a user to adjust the amount of fuel being burned. Preferably the fuel tank is replaceably removable. Ideally, the fuel tank contains fuel that burns as a pressurized gas, even though it may be a liquid at the tank pressures selected. Preferred gases include a gas selected from the group consisting of butane, isobutane, propane, compressed natural gas, and mixtures thereof.
An alternative embodiment of the heated volatile dispenser of the invention is designed for use with a volatile carrier having a volatile-loaded section having a linearly extended volatile-releasing surface. The heated volatile dispenser includes a heat source that preferably is a fuel burner, the heat source generating a convective flow of hot gases, and a carrier holder that holds the volatile carrier within the flow of hot gases in an orientation such that hot gas sweeps over the volatile-releasing surface in a generally vertical direction generally parallel to the direction of linear extension of the volatile-releasing surface to release volatile therefrom. The heated volatile dispenser can also have any or all of the other features described, above.
Preferably a volatile carrier is used that has at least two volatile-releasing surfaces. The carrier holder then is designed to hold the volatile carrier in an orientation such that hot gas sweeps over at least two of the volatile-releasing surfaces at the same time. Most conveniently, the volatile carrier has front and back volatile-releasing surfaces. By way of example, only, a conventional mosquito mat has front and back surfaces, and the carrier holder can be designed to hold a mat edge-on with respect to the flow of hot gases so that gas sweeps over both surfaces of the mat at the same time.
This arrangement has important advantages for the control of temperature across the volatile-releasing surfaces of the volatile carrier. The convective flow of hot gases above a sufficiently hot heater, and especially above a fuel burner that produces both heat and gaseous combustion products, is fast compared to the conductive flow of heat through metal. Consequently, it is believed that the temperature of the hot gases does not drop much as the gases pass over the volatile-releasing surfaces. As a result, the volatile carrier is more evenly heated across its linear expanse so that volatiles are released more uniformly from the entire volatile-releasing surface. When the rate of volatile release from the volatile carrier drops sufficiently low that a fresh carrier is needed, the volatile from the exhausted carrier will have been more completely used than is the case when distinct hotter and cooler regions are formed across the volatile-releasing surfaces.
When the heated volatile dispenser is designed to be used with a volatile carrier having a linearly extended, volatile treated section having a leading edge to be presented toward the flow of hot combustion products, the carrier holder should usually include a heat resistant edge guard that extends along the leading edge of a volatile carrier held in the carrier holder. The edge guard preferably extends the entire length of the leading edge. Alternatively, the edge guard can extend to protect only a portion of the leading edge that is exposed to the hottest area within the flow of hot combustion products, typically located at the center of the leading edge. An edge guard will be understood to be xe2x80x9cheat resistantxe2x80x9d if it does not burn, char, or deform when subjected to the temperatures present at its location within a heated volatile dispenser when that dispenser is in use.
The edge guard protects the leading edge of the volatile carrier from heat directly radiating from fuel burner and from direct, edgeward impact of the flow of hot gases. Also, when the carrier holder has at least two and preferably a front and back volatile-releasing surface, the edge guard helps to split the flow of hot gases to direct the gases across the volatile-releasing surfaces. Either additionally or alternatively, a volatile carrier of the invention intended for such an edge-on orientation can be equipped with a carrier edge guard formed on or attached to the leading edge of the volatile carrier, itself. It is preferred that the edge guard, whether a part of the heated volatile dispenser or attached to the leading edge of the volatile carrier, include deflector vanes extending sidewardly with respect to the direction of linear extension of the volatile carrier""s treated section to disrupt and mix the flow of hot gases before the gases contact the treated section.
A method of the present invention for dispensing ingredients volatilizable by application of heat includes a first step of providing a heated volatile dispenser having (a) a heating chamber having chamber walls and a ceiling with exit vents in either the ceiling or chamber walls communicating between the interior of the heating chamber and the outside air, (b) a fuel burner, (c) a carrier holder to receive and hold a volatile carrier in a location above the fuel burner and contained within the heating chamber, and (d) an air-flow path to guide hot gases from the fuel burner, preferably including combustion products, to direct contact with a volatile carrier held by the carrier holder, the air-flow path being adapted to then direct the hot gases to an exit vent to pass out of the dispenser. A further step of the method is to position in the carrier holder a volatile carrier loaded with the ingredients to be volatilized. A yet further step is to ignite the fuel. This step may be performed either before or after the step of positioning of the volatile carrier in the carrier holder. A final step is to allow the volatile carrier to be heated and the ingredients thus volatilized therefrom to be vented from the dispenser.
An alternative method of the invention for dispensing a volatile material from a volatile carrier having a volatile-loaded section having a linearly extended, volatile-releasing surface includes a first step of providing a heat source, preferably a fuel burner, generating a flow of hot gases and a second step of holding the volatile carrier within the flow of hot gases in an orientation such that hot gas sweeps over the volatile-releasing surface in a direction generally parallel to the direction of linear extension of the volatile-releasing surface. Preferably, the volatile carrier has at least two and preferably both front and back volatile-releasing surfaces and the step of holding the volatile carrier within the flow of hot gases includes holding the volatile carrier in an orientation such that hot gas sweeps over at least two and preferably both the front and back volatile releasing surfaces at the same time.
The invention also includes a volatile-dispensing volatile carrier suitable for use with a heated volatile dispenser having an insert slot through which the volatile carrier must be inserted for use, the insert slot having keying structures that impart a cross-sectional profile to the insert slot that departs from a straight cross-sectional profile and that so restricts access thereto as to prevent the insertion of any volatile carrier not capable of presenting a complementary cross-sectional profile. The volatile carrier of the invention includes a treated section having a cross-sectional profile complementary to that of the insert slot. The volatile carrier also can have a handle having a cross-sectional profile that prevents the handle""s entrance into the insert slot. Preferably the cross-sectional profile of the treated section includes curved or angularly intersecting sections, the latter including (without limitation) slots, prongs, ribs, and the like. Combinations of curved and angularly intersecting sections may also be used. Preferably the volatile carrier is a mat.